Known in the art are cathode ray-tube displays (cf. Kutsenko, Polosjants, Stupitsyn, Minicomputers for Applied Physics, Moscow, 1975, pp. 158-164 [in Russian]) utilizing cathode-ray tubes with magnetic or electrostatic deflection systems and digital beam deflection as well.
In these displays, the data input of a cathode-ray tube is coupled to an output of a control unit via an intensity control unit, whereas vertical and horizontal sweep inputs of the cathode-ray tube are coupled to vertical and horizontal sweep channels, respectively. Each channel incorporates a pulse counter, a digital-analog converter and a pulse amplifier and is coupled to respective remaining output of the control unit. The pulse counters and digital-analog converters of such displays operate to handle conventional binary code data.
The described displays are disadvantageous, since during pulse counting an uncontrollable surge of current or voltage occurs at the output of the digital-analog converter when adjacent codewords (for example 0 1 1 . . . 1 and 1 0 0 . . . 0) are to be replaced. This shows that a powerful transient takes place in the elements of such a display due to the fact that the digit positions of the digital-analog converter are switched over at different times; as a result, the quality of the pattern on the CRT screen deteriorates.
To overcome this harmful effect, the digital-analog converter is provided with a smoothing circuit or the initiation of the electron beam is accomplished under synchronous control. This means that the beam is triggered at time points corresponding to the termination of transients, while time intervals between adjacent beam initiations are chosen depending on the duration of a transient occurred under the most unfavourable conditions. Note that the two methods ensure a better pattern quality but tend to decrease the sweep speed of the beam.
An object of the present invention is to provide for an increased sweep speed of the electron beam and better pattern quality in cathode-ray tube displays by smoothing transients that take place in the components of their digital-analog converters.
Another object of the invention is to create pulse counters and digital-analog converters which could perform Fibonacci code operations.
Still another object of the invention is to provide for a cathode-ray tube display which could be turned off in the case of improper operation of its pulse counters and which is capable of blanking the electron beam during transients.